CN111788464A

CN111788464A - Small form factor spectrally selective absorber with high acceptance angle for gas detection

Info

Publication number: CN111788464A
Application number: CN201780096497.3A
Authority: CN
Inventors: 杨威; 特里萨·M·马尔塔; 伯纳德·弗里茨; 马丁·威利特
Original assignee: Honeywell International Inc
Current assignee: Honeywell International Inc
Priority date: 2017-10-30
Filing date: 2017-10-30
Publication date: 2020-10-16
Also published as: US11119037B2; US20200333244A1; WO2019088976A1; EP3704455A1

Abstract

Embodiments are generally directed to electromagnetic radiation detector devices, systems, and methods using a flat serving cell. A method for gas detection may include: providing a gas sealed in a cavity of a gas detector; directing radiant power from a light source through one or more target gases and through a cell body of the gas detector toward the cavity and wavelength selective absorber of the gas detector, wherein the one or more target gases are positioned between the light source and the cavity; setting a wavelength sensitivity with the wavelength selective absorber, wherein the wavelength sensitivity is independent of an angle of incidence (a); absorbing the radiant power by the wavelength selective absorber and by the one or more target gases; detecting, by a pressure sensing element, a change in pressure due to absorption of the radiant power; and determining the one or more target gases based on the detected pressure change.

Description

Small form factor spectrally selective absorber with high acceptance angle for gas detection

Cross Reference to Related Applications

Not applicable.

Statement regarding federally sponsored research or development

Not applicable.

Reference to attachment of microfiche

Not applicable.

Background

A gravy cell is a type of electromagnetic radiation detector that consists of an enclosure containing a light absorbing material and a flexible diaphragm or film. Which works by converting the absorbed optical radiation into heat causing the absorbing material to expand resulting in a subsequently detectable pressure rise. The conversion from radiation to heat has been achieved by film absorbers, which are not wavelength specific in general.

When using a tall vegetable unit as a detector in, for example, non-dispersive infrared (NDIR) gas detection, it is valuable that the tall vegetable unit has a high spectral correlation with the target gas. One approach is to fill the cell with an IR absorbing gas having the same or similar absorption spectrum as the target gas.

However, gas absorbers have much lower molecular densities than film absorbers, and therefore require much thicker gas layers to achieve adequate absorption. Furthermore, when the same level of absorption is achieved, the gas layer will have a greater heat capacity than the solid film, and therefore a lower temperature rise and sensitivity.

In many applications, it is also desirable for the detector to have a planar or small overall form factor, which is difficult to achieve when long optical path lengths are required for the gas absorber. Alternatively, while a film absorber with an external filter would provide spectral selectivity, it tends to be expensive and the filter is typically sensitive to the angle of the incident light.

Disclosure of Invention

In one embodiment, an electromagnetic radiation detection apparatus using a planar tall dish unit may include: a cell body forming a cavity therein, wherein the cavity contains a wavelength selective absorber having a predetermined absorption spectral range and configured to absorb radiation regardless of an angle of incidence, and the cavity is filled with a gas; and a pressure sensing element fluidly connected to the cavity to measure pressure changes within the cavity.

In one embodiment, a method for using a tall dish unit may comprise: directing radiant power from a light source through at least a portion of a cell body of the electromagnetic radiation detection apparatus toward the gas cavity and the wavelength selective absorber, the wavelength selective absorber configured to absorb radiation regardless of angle of incidence, wherein the optical path of the radiant power passes through one or more target gases before reaching the wavelength selective absorber; absorbing at least a portion of the radiant power by the wavelength selective absorber or a gas within the gas cavity; detecting, by a pressure sensing element, a change in pressure due to absorption of the radiant power; and determining a kind of the one or more target gases and quantifying the one or more target gases based on the detected pressure change.

In one embodiment, an electromagnetic radiation detection apparatus using a planar tall dish unit may include: a cell body in which a cavity is formed, wherein the cavity contains a wavelength selective absorber having a predetermined absorption spectral range and configured to absorb radiation regardless of angle of incidence, and the cavity is filled with a gas having specific thermal and thermal conductivity characteristics, and wherein at least a portion of the cell body transmits at least the predetermined absorption spectral range; and a pressure sensing element fluidly connected to the cavity to measure pressure changes within the cavity.

Drawings

For a more complete understanding of this disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts.

Fig. 1A illustrates an electromagnetic radiation detection apparatus according to one or more embodiments of the present disclosure.

Fig. 1B illustrates a stacked electromagnetic radiation detection apparatus according to one or more embodiments of the present disclosure. It should be noted that this exemplary view is an exploded view with the angle of incidence enlarged to show details. In practice, the stack will be significantly thinner (in height) than the stack shown.

Fig. 2 illustrates another electromagnetic radiation detection apparatus in accordance with one or more embodiments of the present disclosure.

Fig. 3 illustrates a front view of a ring reflector according to embodiments of the present disclosure.

Fig. 4A and 4B illustrate a ring reflector assembled with electronic components including a printed circuit board according to embodiments of the present disclosure.

Detailed Description

It should be understood at the outset that although an illustrative implementation of one or more embodiments are illustrated below, the disclosed systems and methods may be implemented using any number of techniques, whether currently known or in existence. The present disclosure should in no way be limited to the exemplary embodiments, drawings, and techniques illustrated below, but may be modified within the scope of the appended claims along with their full scope of equivalents.

The following brief term definitions shall apply throughout the specification:

the term "including" means including but not limited to, and should be interpreted in the manner commonly used in the patent context;

the phrases "in one embodiment," "according to one embodiment," and the like generally mean that a particular feature, structure, or characteristic following the phrase may be included in at least one embodiment of the present invention, and may be included in more than one embodiment of the present invention (importantly, such phrases do not necessarily refer to the same embodiment);

if the specification describes something as "exemplary" or "an example," it should be understood to mean a non-exclusive example;

the terms "about" or "approximately" and the like, when used in conjunction with a number, may mean the particular number, or alternatively, a range near the particular number, as understood by those skilled in the art; and

if the specification states a component or feature "may", "can", "should", "will", "preferably", "possibly", "generally", "optionally", "e.g." often "or" may "(or other such words) be included or have a characteristic, that particular component or feature does not necessarily have to be included or have that characteristic. Such components or features may optionally be included in some embodiments, or may be excluded.

Typical non-dispersive infrared ("NDIR") detectors use a method for filtering unwanted wavelengths from the infrared ("IR") detector. In some embodiments, a narrow-band interference filter is used to define one or more wavelength ranges of interest. In general, the best performance of an optical filter is at near normal incidence when light passes through the filter. This is not always possible in optical systems where light is incident on the detector/detection device and is particularly a problem for small optical sensors. Light incident on the detector at increasing angles of incidence relative to the normal will cause a spectral (bandpass) shift of the filter to shorter wavelengths. Depending on the light source used, the p-polarization properties and the s-polarization properties may also be influenced by the plane of incidence. Furthermore, narrow band pass filters can change wavelength and absorbance with changes in temperature, which can be significant. The band pass filter and its temperature coefficient are defined at normal incidence. In addition to broadening performance, high angles of incidence also introduce elements of higher variability that are not easily compensated for. The use of narrow-band thin-film interference filters places additional demands on the optical system.

The present disclosure highlights the additional advantage of being insensitive to incident angles. When using a solid absorber in a flat gravy cell, the light is given wavelength specificity without the need to also allow transmission, so that all rays contribute to the signal as long as they hit the absorber, regardless of the angle of incidence. The systems, methods, and apparatus of the present disclosure may relax the optical design, especially when there is a high angle of incidence at the detector. The use of a band pass filter can impose a limit on the flux of the optical system by limiting the acceptance angle. This is the case for dichroic filters (thin films) which can typically have a cone angle limit of 20 degrees. This limit imposes constraints on the optical system, such as the need to increase the overall length of the optical system to achieve a given flux, or the need for a low-angle emission source. In many designs, especially compact designs, the desire to capture as much light as possible from a poorly collimated/inefficient light source tends to create these high angles, which exacerbate potential problems. By using an absorption-based band-pass filter with no angular limitation on flux, a much smaller sensor can be realized at high flux.

Embodiments of the present disclosure include electromagnetic radiation devices, systems, and methods using a flat serving unit. The present disclosure describes a spectrally selective film absorber (e.g., a wavelength selective absorber) that, in some embodiments, will enable the construction of planar tall dish units with specific spectral characteristics and extremely small form factors.

One area in which embodiments of the present disclosure may be advantageous is NDIR gas detection, where a flat gay dish unit may be used as a detector. Embodiments for such applications provide the advantage of being planar, which may allow multiple cells to be stacked together, and may enable them to be used in compact designs. In addition, spectral selectivity allows embodiments specific to the desired analyte gas. This may allow specialized applications and uses, for example, to reduce emissions from ambient gases such as carbon dioxide (CO)₂) Or water) or more accurately detect the gas.

An apparatus includes a cell body forming a cavity therein. The cavity may contain a wavelength selective absorber (or film wavelength selective absorber) having a predetermined absorption spectral range and configured to absorb radiation regardless of the angle of incidence, and may be filled with a gas having specific thermal and thermal conductivity characteristics. The cell body is transmissive to at least a predetermined absorption spectral range, and a pressure sensing element is fluidly connectable to the cavity to measure pressure changes within the cavity.

For example, in some embodiments, a planar tall dish unit that is sensitive to the wavelength to which hydrocarbon absorption corresponds is shown in the figures. The unit may have a suspended thin film polymeric absorber, which may conveniently be made from a foil of, for example, polyethylene, polypropylene or other polymeric material having a particular desired absorption spectrum. The cell may be filled with a gas of low specific heat and low thermal conductivity, such as, for example, argon, krypton or xenon.

In some embodiments, the total volume of gas may be kept relatively small. For example, the spacing between the polymer film and the cell body may be between about 0.05mm and about 0.2 mm.

The film thickness may be comparable to or less than the light absorption length. For example, a suitable thickness may be between about 5 microns and about 15 microns. When incident light is absorbed by the film, the film may be heated to a temperature above ambient temperature. In this way the enclosed gas will subsequently be heated to almost the same temperature as the temperature of the membrane. The pressure rise of the heated gas may then be detected by a microphone fluidly connected to the unit. The resulting responses measured by the microphones can then be used to determine the concentration of the gas in the light path.

More specifically, the incident light may be modulated at a predetermined frequency to produce a resulting modulated pressure rise and fall within the cavity. The resulting pressure signal may then be detected at a predetermined modulation frequency, and the amplitude of the resulting modulation signal may be used to determine various characteristics of light absorption between the light source and the cell. In general, a decreasing signal will tend to indicate an increase in the concentration of gas absorbed at a particular wavelength absorbed by the film between the light source and the cell, with the absorption in the gas reducing the amount of light reaching the film and thus reducing the output response.

Referring now to FIG. 1A, an electromagnetic radiation detection apparatus 100 is shown. In the embodiment of fig. 1A, the wavelength selective absorber 101 is held in place by a spacer 104. On the end of the cell body 114, the diaphragm 104 also includes at least one pressure sensing aperture 108 in fluid communication with the cavity 112 such that the pressure sensing element 102 (e.g., a pressure sensor) can sense pressure changes within the cavity 112 via the pressure sensing aperture 108.

In various embodiments of the present disclosure, at least a portion of the cell body 114 is transmissive to electromagnetic radiation. For example, the cell body 114 may be opaque to all light that is not within a particular wavelength range (such as those wavelengths that indicate the presence of a particular target gas). It should be noted that embodiments of the present disclosure are not limited to gas detection, and may be used to detect other items that may be discerned using such devices.

Some embodiments may be used to distinguish particular gases, and thus the electromagnetic radiation detection apparatus 100 may be sensitive to a predetermined absorption spectral range that includes the spectral range of one or more gases that are the target of sensing. Thus, in some embodiments, at least a portion of the cell body 114 is transmissive to only the predetermined absorption spectral range or is transmissive to at least the predetermined absorption spectral range.

In some embodiments, the cell body 114 can include optical properties that alter the properties of light passing through the cell body 114. For example, the cell body 114 may have diffusing or collimating properties designed into the cell body 114. In some embodiments, the cell body 114 may also be a lens or a waveguide.

These optical characteristics may be based on forming the interior of the cell body 114, forming and/or preparing (e.g., polishing) one or more sides of the cell body 114, and/or by using coatings applied to the cell body 114 on one or more sides. The cell body 114 may also be coated with an optical film to enhance or block the transmission of certain wavelengths of light. This may facilitate separation or in some embodimentsCertain wavelengths are focused for the purpose of improved detection. For example, certain wavelengths that may be separated or enhanced may be 3.3 and/or 3.4 microns for hydrocarbons and 3.4 microns for CO₂May be 4.3 microns, or for ammonia may be 9 microns, etc.

In various embodiments of the present disclosure, the cavity 112 may be a closed unit that does not allow interaction with the surrounding environment. Thus, the gas 120 within the cavity 112 may be selected to enhance sensitivity to the presence of a particular gas or set of gases.

In some embodiments, the cavity 112 is sealed such that once the cavity 112 is sealed, ambient (or any other) gas cannot enter the cavity. The cavity 112 may also be sealed such that once the cavity 112 is sealed, gas cannot leak out of the cavity. In some such implementations, the pressure sensing element 102 and/or the cell body 114 may be attached such that the cavity 112 is hermetically sealed. Such embodiments allow for the formation of a gas-filled cavity 112 that is fluidly connected to the pressure sensing bore 108 (e.g., microphone inlet port) but isolated from ambient conditions.

In some embodiments, the gas 120 within the cavity 112 may be known, and the electromagnetic radiation detection apparatus 100 may be configured to determine the type and amount of gas positioned within individual gas chambers through which the light source 130 may be directed. In some embodiments, the gas being measured may be present at any point between the light source 130 and the cavity 112, with or without confinement to a particular chamber. In some embodiments, the gas being measured may be in the open/ambient air between the light source 130 and the cavity 112.

As shown in fig. 1A, the cavity 112 of the planar high-gain device may have two sides 112-1 and 112-2 separated by a wavelength selective absorber 101. In such embodiments, the electromagnetic radiation detection apparatus 100 may also be provided with a through hole 103 to allow fluid connection between the two sides 112-1 and 112-2 of the cavity 112 separated by the wavelength selective absorber 101.

In the embodiment of FIG. 1A, a through-hole 103 may be formed in the cell body 114 (e.g., the septum 104) to allow a fluid (e.g., a gas 120 within the cavity 112) to move between the two sides 112-1 and 112-2 of the cavity 112. In this way, the pressure between the two sides 112-1 and 112-2 may be equalized, among other benefits. When radiant power 116 (e.g., light from light source 130) enters the cavity 112 through the cell body 114 and is absorbed by the gas 120 and/or the surface of the wavelength selective absorber 101, a small amount of heat may be generated. This heat causes a rise in pressure that can be sensed by the pressure sensing element 102. It should be noted that the radiant power 116 may contact the wavelength selective absorber 101 at any angle of incidence α, as shown in fig. 1A, 1B, and 2. All rays of the radiation power 116 that contact the wavelength selective absorber 101 contribute to the generation of the pressure signal independent of the angle of incidence α. The wavelength sensitivity may be set with the wavelength selective absorber 101.

The gas 120 in the cavity 112 may be selected to optimize the sensitivity and/or temperature range of the detector apparatus 100 based on parameters such as specific heat, thermal conductivity, permeability, triple point, and/or chemical stability, among other parameters that may be used based on the operating conditions of the electromagnetic radiation detection apparatus 100. The gas 120 may be, for example, nitrogen, hydrogen, argon, krypton, xenon, a hydrocarbon, a fluorocarbon, or a mixture of the above gases, as well as other suitable gas types. In various embodiments, the pressure of the gas 120 may be less than or greater than ambient pressure. For example, in some embodiments, the gas 120 pressure may be in the range of 0.1 bar to 10 bar.

An advantage of the electromagnetic radiation detection apparatus 100 is that the microphone (or pressure sensing element) 102 is isolated from the surrounding environment, thereby eliminating interference and instability due to environmental variables such as acoustic noise, pressure, density, moisture, chemicals, and particles in the surrounding environment near the electromagnetic radiation detection apparatus 100. This may be accomplished by sealing the pressure sensing element 102 around the pressure sensing bore 108. Additionally, this may be accomplished by a cap 106 positioned around the pressure sensing element 102.

Referring now to fig. 1B, in some applications, there may be several electromagnetic radiation detector devices 100 (e.g., on the same substrate, such as a Printed Circuit Board (PCB)), each having a different gas 120 in its respective cavity 112, and which may be inserted into a larger system to enable gas detection. Additionally, in some embodiments, a single electromagnetic radiation detection apparatus 100 (e.g., the structure of fig. 1A or a similar structure) may be used in the system, and the electromagnetic radiation detection apparatus 100 may be removed and replaced with another apparatus that may sense one or more other gases. In other embodiments, multiple electromagnetic radiation detector devices 100 may be used simultaneously in the system 150 to sense multiple gases or may have the same gas 120 in the chamber 112 and may provide redundancy, which may be beneficial as it will provide increased certainty of correcting gas detection. In some embodiments, at least one of the devices 100 may be used as a reference. In some embodiments, a single light source 130 may be used to direct radiation or light through multiple electromagnetic radiation detector devices 100, where each unit body 114 may be transparent to a range of wavelengths. In some embodiments, the electromagnetic radiation detector devices 100 may be placed in a particular order such that wavelengths rejected by the wavelength selective absorber 101 may be absorbed in a particular order. Each of the electromagnetic radiation detector devices 100 may function as described in fig. 1A.

Fig. 2 illustrates another electromagnetic radiation detector device 200 according to one or more embodiments of the present disclosure. Similar to the embodiment of fig. 1A, in the embodiment shown in fig. 2, the electromagnetic radiation detector device 200 includes a unit body 214 having a cavity 212 formed therein, the unit body having a wavelength selective absorber 201 and a pressure sensing element 202 (e.g., a microphone) having a pressure sensing aperture 208 in fluid communication with the cavity 212.

In one embodiment, the unit body 214 has a front 213 and a rear 215, wherein the pressure sensing element 202 is positioned on the rear of the unit body 215, which further includes a pressure sensing bore 208 in fluid communication with the cavity 212 such that the pressure sensing element 202 can sense pressure changes within the cavity 212 via the pressure sensing bore 208. Although not required, the wavelength selective absorber 201 is also shown aligned along the central elongated axis of the cell body 214. In the embodiment of fig. 2, the wavelength selective absorber 201 is also held in place by a spacer 204.

In some embodiments, the gas 220 within the cavity 212 may be known, and the electromagnetic radiation detector apparatus 200 may be configured to determine the characteristics and/or type of gas positioned within individual gas chambers through which the light sources 230 may be directed. In some embodiments, the gas being measured may be present at any point between the light source 230 and the cavity 212, with or without confinement to a particular chamber. In some embodiments, the gas being measured may be in the open/ambient air between the light source 230 and the cavity 212.

When radiant power 216 (e.g., light from the light source 230) enters the cavity 212 through the cell body 214 and is absorbed by the gas 220 and/or the wavelength selective absorber 201 surface, a small amount of heat may be generated. As with the embodiment of fig. 1A, this heat causes a pressure rise that can be sensed by the pressure sensing element 202 via the pressure sensing aperture 208. As discussed above with respect to FIG. 1A, the embodiment of FIG. 2 also includes one or more through-holes 203 to allow fluid connection between the two sides 212-1 and 212-2 of the cavity separated by the wavelength selective absorber 201. In the embodiment of FIG. 2, through-holes 203 may be formed in the wavelength selective absorber 201 (and reflective element 217) to allow fluid (e.g., gas 220 within the cavity 212) to move between the two sides 212-1 and 212-2 of the cavity 212. In this way, the pressure between the two sides 212-1 and 212-2 may be balanced, among other benefits. In some embodiments, this functionality may be provided by other methods. For example, the wavelength selective absorber 201 may be air permeable, or microchannels may be provided in the wavelength selective absorber 201 or the cell body 214.

Embodiments disclosed herein may be coupled with a light source 230. For example, a suitable light source 230 may be one or more filament bulbs, micro-electro-mechanical systems (MEMS) hot plates, Light Emitting Diodes (LEDs), and/or lasers. Such components can all potentially be advantageously collocated with the detector embodiments described herein to provide a gas sensor with good performance.

In the embodiment of fig. 2, a reflective element 217 (e.g., a reflector) is also provided, positioned on the back side of the wavelength selective absorber 201. In some embodiments, the reflective element 217 may be near the back surface of the wavelength selective absorber 201, but need not be adjacent or connected thereto. Additionally, a reflective element 217 may be positioned on at least one side of the wavelength selective absorber 201. This may be beneficial, for example, because the reflection may be only a partial reflection of the light impinging on the reflective element 217 and/or it may be applied to multiple sides of the wavelength selective absorber 201 to enhance some characteristics of the light within the cavity.

In all applications, reflective element 217 need not reflect visible light, but may reflect one or more wavelengths that will be used with respect to a particular gas or gases within detection cavity 212. The reflective element 217 may be beneficial, for example, to reduce environmental noise (e.g., audible noise, thermal noise (i.e., heating components), parasitic noise) that may impinge on the pressure sensing bore 208 via the front surface 213 of the unit body 214. In terms of noise, the pressure sensing element 202 responds only to changes conveyed by changes in the gas. The primary mechanism for controlling the location of the absorbed light is the wavelength selective absorber 201 rather than other components such as, for example, sidewalls, windows, sensing devices, and the like. It should be noted that fig. 2 is an exemplary configuration of an electromagnetic radiation detector apparatus, and not the only suitable configuration. With respect to the configuration shown in fig. 2, the placement of the reflective element 217 prevents light from entering the microphone (e.g., pressure sensing element 202) through the fluid connection (e.g., pressure sensing aperture 208), which may generate a "background" signal independent of the absorber (e.g., wavelength selective absorber 201). To be sensitive to a particular gas, an optical band pass filter can be added as an additional component in the optical path or as a coating on the inner surface (closer to the pressure sensing element 202) or the outer surface (or front surface 213) of the cell body 214. In some cases, even if the cavity 212 has a particular gas 220 therein, it may be desirable to filter out environmental elements that may have similar characteristics as the particular gas 220 in the cavity 212.

In such cases, one or more filters, such as a film, applied coating, filter physically separated from the cell body, or other type of filter, may be placed in the optical path of the radiant power 216 from the light source to filter out ambient noise, such as, for example, audible noise, thermal noise (i.e., heating components), and spurious noise (optical path)The characteristic of possible error in the target gas). Such embodiments may also be accomplished in applications where multiple gases 220 are within the chamber 212. Examples of environmental elements that may be leached may include, for example, CO₂Water vapor or condensed water, and the like. Types of filters used for purge gas analysis may include mechanical filters, such as, for example, dust or other types of particulate filters, and optical filters for interference effects (e.g., absorptive, interference, dichroic, band pass, or endothermic filters).

In one embodiment, the light source 230 may emit narrow or broadband electromagnetic radiation in the infrared region. In one embodiment, the light source 230 may include an incandescent lamp, a blackbody radiation source, or another emitter of electromagnetic radiation in the infrared spectrum. In some embodiments, the light source 230 may be a Light Emitting Diode (LED), an LED array, a laser diode, or the like. In one embodiment, light source 230 may generate broadband radiation in the infrared range.

The radiation 216 from the light source 230 may be modulated to provide an acoustic response in the gas cavity 212. Various types of modulators may be used. In one embodiment, the light source 230 may be modulated and/or the radiation 216 may be mechanically or electrically modulated after the light source 230 generates the radiation. For example, the controller may control the power signal to the light source 230 to produce a modulated radiation output. The radiation 216 may also be modulated after it is generated by the light source 230, including using a modulation mechanism such as a mechanical chopper (e.g., a rotating disk having a channel therethrough, a rotating mirror, etc.), an interference grating or filter, an interferometer, or the like. In some embodiments, an optical modulator may also be used to modulate the radiation 216 from the light source 230, including but not limited to acousto-optic modulation, electro-optic modulation, magneto-optic modulation, and the like.

The radiation 216 may allow the frequency at which the acoustic signal is detected to be modulated, and the detection limit of the acoustic sensor, as well as any background noise, may be considered when selecting the modulation rate. The radiation 216 may be modulated at a frequency of at least about 1Hz or at least about 10Hz, but in some embodiments, the radiation 216 may be modulated at a lower frequency. In some embodiments, radiation 103 may be modulated at a higher frequency in order to reduce the sensitivity of photoacoustic sensor 100 to acoustic background noise. In one embodiment, the radiation 216 may be modulated at a frequency between 3Hz and 10,000 Hz.

The electromagnetic radiation detector device 200 of this configuration may operate at very low power because the planar tall dish unit is able to detect a very low level of radiant power 216 and thus the light source 230 may be energized at a correspondingly low level.

Fig. 3 shows a front view of a ring reflector 300. A toroidal reflector 300 is shown comprising an emitter 302 and an electromagnetic radiation detection device 100, wherein radiated power 304 from the emitter 302 is reflected from a curved wall 306 of the toroidal reflector 300 towards the electromagnetic radiation detection device 100. Fig. 3 illustrates how radiated power 304 generates more than one focal point at electromagnetic radiation detection apparatus 100 due to the propagation of radiated power 304. The outer diameter of the ring reflector 300 may be in the range of about 10mm to about 20mm (e.g., 16 mm). It should be noted that other electromagnetic radiation detector devices, such as, for example, electromagnetic radiation detector device 200, may be utilized within toroidal reflector 300 in place of electromagnetic radiation detection device 100. All rays of the radiation power 304 contribute to the signal as long as each ray of the radiation power 304 hits/contacts the wavelength selective absorber 101 (as shown in fig. 1A and 1B) of the electromagnetic radiation detector apparatus 100, independent of the angle of incidence α.

Fig. 4A-4B illustrate a ring reflector 300 assembled with electronic components, including a printed circuit board ("PCB") 308. The emitter 302 and the electromagnetic radiation detection apparatus 100 may be attached to one or

more connectors

310 and 312 configured to allow communication between the emitter 302, the electromagnetic radiation detection apparatus 100, and the PCB 308.

Embodiments of the present disclosure may be configured as a miniature golay detector device, wherein the width of the widest side of the pressure sensing element (i.e., the largest dimension of the pressure sensing element) may be about 2-5 mm. For such embodiments, these devices may be used for small and/or portable applications, and such devices may have low power consumption when compared to devices having width dimensions of 10-20mm in magnitude. Another benefit of miniature golay devices is a reduced ability for contaminants to enter the device, as well as a reduction in environmental noise.

Embodiments of the present disclosure may be used for a wide range of optical-based gas detection, including detection of flammable, toxic, and other environmentally relevant gases such as CO₂And a refrigerant. For example, the planar tall vegetable unit detector device may be used as a stand-alone detector of electromagnetic radiation from deep UV to terahertz frequencies, among other embodiments.

Some embodiments of the present disclosure may include methods for assembling and/or using an electromagnetic radiation detector device (as described above). These methods may include assembling elements of the detector device as described in fig. 1A-2. Additionally, gas may be allowed to enter the cavity of the device. The cavity may then be sealed so that gas cannot enter or exit the cavity. A light source may be directed at the device, where the light source may pass through at least a portion of the cell body. The gas and/or wavelength selective absorber may absorb at least a portion of the radiation from the light source and may generate heat as a result of the absorption. The generated heat may cause a pressure change that may be detected by a pressure sensing element in fluid communication with a lumen of the device. The detected pressure change may be related to the amount of radiation absorbed by the gas, and the type of gas may be determined. That is, the amount of radiation absorbed by the gas and the type of gas may be determined based on the detected pressure change.

In another embodiment, the light source may be directed through another gas chamber separate from the cavity, wherein the target gas may be positioned in the gas chamber.

In a first embodiment, an electromagnetic radiation detector device using a planar tall dish unit may comprise: a cell body forming a cavity therein, wherein the cavity contains a wavelength selective absorber having a predetermined absorption spectral range and configured to absorb radiation regardless of an angle of incidence, and the cavity is filled with a gas; and a pressure sensing element fluidly connected to the cavity to measure pressure changes within the cavity.

A second embodiment may include the apparatus of the first embodiment, wherein the pressure sensing element is a microphone.

A third embodiment may include the device of the first or second embodiment, wherein the cell body is opaque to all light not within a particular wavelength range.

A fourth embodiment may include the apparatus of any of the first to third embodiments, wherein the cavity is sealed such that once the cavity is sealed, no ambient gas can enter the cavity.

A fifth embodiment may include the apparatus of any one of the first to fourth embodiments, wherein the cavity is filled with a gas having low specific heat characteristics.

A sixth embodiment may include the apparatus of any of the first to fifth embodiments, wherein the cavity is filled with a gas having low thermal conductivity characteristics.

A seventh embodiment may include the apparatus of any of the first to sixth embodiments, wherein the pressure sensing element and the cell body are bonded together and hermetically sealed from the surrounding environment.

An eighth embodiment may include the sensor of any one of the first to seventh embodiments, wherein the wavelength selective absorber is a polyethylene material.

A ninth embodiment may include the apparatus of any one of the first to eighth embodiments, wherein the wavelength selective absorber is a polypropylene material.

A tenth embodiment may include the apparatus of any of the first to ninth embodiments, wherein the apparatus further comprises a reflective element on at least one side of the wavelength selective absorber.

An eleventh embodiment can include the device of any of the first to tenth embodiments, wherein the pressure sensing element is positioned on a rear side of the cell body.

A twelfth embodiment may include the device of any of the first to eleventh embodiments, wherein the device includes a hole through the back side of the unit body that provides fluid communication between the pressure sensing element and the cavity.

A thirteenth embodiment may include the apparatus of any one of the first to twelfth embodiments, wherein the cavity has two sides, and wherein at least one of the wavelength selective absorber or unit body includes one or more through holes to allow fluid connection between the two sides of the cavity.

A fourteenth embodiment can include the apparatus of any of the first to thirteenth embodiments, wherein the wavelength selective absorber is tensioned and supported within the cell body.

A fifteenth embodiment may include the apparatus of any of the first to fourteenth embodiments, further comprising a plurality of planar tall dish units, wherein the unit bodies of the plurality of tall dish units are stacked against one another, wherein the pressure sensing elements of the tall dish units are positioned adjacent the stacked side of the unit bodies, and wherein radiation from a single light source is directed through the plurality of tall dish units.

In a sixteenth embodiment, a method for using a tall dish unit can comprise: directing radiant power from a light source through at least a portion of a cell body of the detector toward the gas cavity and the wavelength selective absorber, the wavelength selective absorber configured to absorb radiation regardless of angle of incidence, wherein the optical path of the radiant power passes through one or more target gases before reaching the wavelength selective absorber; absorbing at least a portion of the radiant power by the wavelength selective absorber or a gas within the gas cavity; detecting, by a pressure sensing element, a change in pressure due to absorption of the radiant power; and determining a species of the one or more target gases based on the detected pressure change.

A seventeenth embodiment may include the method of the sixteenth embodiment, further comprising adding a wavelength selective absorber within the gas cavity of the detector; allowing one or more gases to enter the gas cavity of the detector; and hermetically sealing the gas cavity and the pressure sensing element from an ambient environment.

An eighteenth embodiment may include the method of the seventeenth embodiment, further comprising assembling a reflective element on at least one surface of the wavelength selective absorber.

A nineteenth embodiment may include the method of any one of the twelfth to eighteenth embodiments, further comprising assembling the pressure sensing element with a Printed Circuit Board (PCB).

In a twentieth embodiment, an electromagnetic radiation detector apparatus using a planar tall dish unit may comprise: a cell body in which a cavity is formed, wherein the cavity contains a wavelength selective absorber having a predetermined absorption spectral range and configured to absorb radiation regardless of angle of incidence, and the cavity is filled with a gas having specific thermal and thermal conductivity characteristics, and wherein at least a portion of the cell body transmits at least the predetermined absorption spectral range; and a pressure sensing element fluidly connected to the cavity to measure pressure changes within the cavity.

In a twenty-first embodiment, a method for gas detection comprises: providing a gas sealed in a cavity of a gas detector; directing radiant power from a light source through one or more target gases and through a cell body of the gas detector toward the cavity and wavelength selective absorber of the gas detector, wherein the one or more target gases are positioned between the light source and the cavity; setting a wavelength sensitivity with the wavelength selective absorber (101), wherein the wavelength sensitivity is independent of an angle of incidence (a); absorbing the radiant power by the wavelength selective absorber and by the one or more target gases; detecting, by a pressure sensing element, a change in pressure due to absorption of the radiant power; and determining the one or more target gases based on the detected pressure change.

A twenty-second embodiment may include the method of the twenty-first embodiment, further comprising determining an amount of radiation absorbed by the one or more target gases based on the detected pressure change.

A twenty-third embodiment may include the method of the twenty-first or twenty-second embodiment, further comprising generating heat as a result of the absorption.

A twenty-fourth embodiment may include the method of any of the twenty-first to twenty-third embodiments, further comprising filtering CO from the optical path of the radiant power with a particle filter or an optical filter₂Water vapor or condensed water.

A twenty-fifth embodiment may include the method of any one of the twenty-first to twenty-fourth embodiments, further comprising modulating the radiant power optically, electrically, or mechanically.

A twenty-sixth embodiment may include the method of any of the twenty-first to twenty-fifth embodiments, further comprising modulating the radiated power (116) at a frequency of at least about 1 Hz.

A twenty-seventh embodiment may include the method of any one of the twenty-first to twenty-sixth embodiments, further comprising reflecting or refracting the radiant power through the one or more target gases and through the cell body of the gas detector toward the cavity of the gas detector and the wavelength selective absorber with a reflector or refractive element.

In a twenty-eighth embodiment, a method for gas detection comprises: providing a gas sealed in a cavity of a gas detector; directing radiant power from a light source through one or more target gases and through a cell body of the gas detector toward the cavity and wavelength selective absorber of the gas detector, wherein the one or more target gases are positioned between the light source and the cavity; reflecting the radiant power through the one or more target gases and through the cell body of the gas detector toward the cavity of the gas detector and the wavelength selective absorber with a reflector; setting a wavelength sensitivity with the wavelength selective absorber, wherein the wavelength sensitivity is independent of an angle of incidence (a); absorbing the radiant power by the wavelength selective absorber and by the one or more target gases; detecting, by a pressure sensing element, a change in pressure due to absorption of the radiant power; and determining the one or more target gases based on the detected pressure change.

A twenty-ninth embodiment may include the method of the twenty-eighth embodiment, further comprising providing fluid communication between the pressure sensing element and the cavity.

A thirtieth embodiment may include the method of the twenty-eighth or twenty-ninth embodiment, further comprising allowing fluid connection between two sides of the cavity via a through-hole.

A thirty-first embodiment may include the method of any one of the twenty-eighth to thirty-first embodiments, further comprising determining an amount of radiation absorbed by the one or more target gases based on the detected pressure change.

A thirty-second embodiment may include the method of any one of the twenty-eighth to thirty-first embodiments, further comprising modulating the radiated power (116) at a frequency between 3Hz and 10,000 Hz.

A thirty-third embodiment may include the method of any one of the twenty-eighth to thirty-second embodiments, wherein the providing a gas sealed in a cavity (112) comprises providing nitrogen, hydrogen, argon, krypton, xenon, a hydrocarbon, a fluorocarbon, or a combination thereof.

A thirty-fourth embodiment may include the method of any one of the twenty-eighth to thirty-third embodiments, further comprising pressurizing the gas sealed in the cavity (112) at a pressure in the range of 0.1 bar to 10 bar.

A thirty-fifth embodiment may include the method of any one of the twenty-eighth to thirty-fourth embodiments, wherein directing radiant power from a light source comprises directing radiant power from one or more filament bulbs, micro-electro-mechanical system (MEMS) heating plates, Light Emitting Diodes (LEDs), and/or lasers.

While various embodiments in accordance with the principles disclosed herein have been shown and described above, modifications thereof can be made by one skilled in the art without departing from the spirit and teachings of the disclosure. The embodiments described herein are merely representative and are not intended to be limiting. Many variations, combinations, and modifications are possible and are within the scope of the disclosure. Alternative embodiments resulting from the incorporation, integration, and/or omission of features of one or more embodiments are also within the scope of the present disclosure. Accordingly, the scope of protection is not limited by the description set out above, but is instead defined by the claims which follow, that scope including all equivalents of the subject matter of the claims. Each claim is incorporated into the specification as a further disclosure and a claim is one or more embodiments of the invention. Moreover, any of the above advantages and features may be related to particular embodiments, but the application of such issued claims should not be limited to methods and structures accomplishing any or all of the above advantages or having any or all of the above features.

In addition, the section headings used herein are for consistency with the suggestions of 37 c.f.r.1.77 or to provide organizational cues. These headings should not limit or characterize the invention(s) set forth in any claims that may issue from this disclosure. In particular and by way of example, although a title may refer to a "technical field," the claims should not be limited by the language chosen under this title to describe the so-called field. Furthermore, the description of technology in the "background" should not be read as an admission that certain technology is prior art to any one or more of the inventions in this disclosure. "brief summary" is also not to be considered a limiting characterization of one or more inventions set forth in the published claims. Furthermore, any reference in this disclosure to the singular form of "an invention" should not be used to qualify as only one point of novelty in this disclosure. Multiple inventions may be set forth according to the limitations of the multiple claims issuing from this disclosure, and such claims accordingly define the invention(s) protected thereby and their equivalents. In all cases, the scope of these claims should be considered in light of the present disclosure in light of the advantages of the claims themselves, and should not be limited by the headings set forth herein.

It is to be understood that the use of broad terms such as "comprising," including, "and" having "provides support for terms in a narrow sense such as" consisting of …, "" consisting essentially of …, "and" consisting essentially of …. Use of the terms "optionally," "may," "potentially," and the like, with respect to any element of an embodiment, means that the element is not required, or alternatively, the element is required, both alternatives being within the scope of one or more embodiments. Additionally, references to examples are for illustrative purposes only and are not intended to be exclusive.

While several embodiments are provided in the present disclosure, it should be understood that the disclosed systems and methods may be embodied in many other specific forms without departing from the spirit or scope of the present disclosure. The present examples are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein. For example, various elements or components may be combined or integrated in another system or certain features may be omitted, or not implemented.

Moreover, techniques, systems, subsystems, and methods described and illustrated in the various embodiments as discrete or separate may be combined or integrated with other systems, modules, techniques, or methods without departing from the scope of the present disclosure. Other items shown or discussed as directly coupled or communicating with each other may be indirectly coupled or communicating through some interface, device, or intermediate component whether electrically, mechanically, or otherwise. Other examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and could be made without departing from the spirit and scope disclosed herein.

Claims

1. A method for gas detection, comprising:

providing a gas sealed in a cavity (112) of a gas detector (100);

directing radiant power (116) from a light source (130) through one or more target gases and through a cell body (114) of the gas detector (100) toward the cavity (112) and wavelength selective absorber (101) of the gas detector (100), wherein the one or more target gases are positioned between the light source (130) and the cavity (112);

setting a wavelength sensitivity with the wavelength selective absorber (101), wherein the wavelength sensitivity is independent of an angle of incidence (a);

absorbing the radiant power (116) by the wavelength selective absorber (101) and by the one or more target gases;

detecting, by a pressure sensing element (102), a pressure change due to absorption of the radiant power (116); and

determining the one or more target gases based on the detected pressure change.

2. The method of claim 1, further comprising determining an amount of radiation absorbed by the one or more target gases based on the detected pressure change.

3. The method of claim 1, further comprising generating heat as a result of the absorbing.

4. The method of claim 1, further comprising filtering CO from an optical path of the radiant power (116) with a particle filter or an optical filter₂Water vapor or condensed water.

5. The method of claim 1, further comprising modulating the radiant power (116) optically, electrically, or mechanically.

6. The method of claim 1, further comprising modulating the radiated power (116) at a frequency of at least about 1 Hz.

7. The method of claim 1, further comprising reflecting or refracting the radiant power (116) through the one or more target gases and through the cell body (114) of the gas detector (100) toward the cavity (112) of the gas detector (100) and the wavelength selective absorber (101) with a reflector or refractive element.

8. A method for gas detection, comprising:

providing a gas sealed in a cavity (112) of a gas detector (100);

reflecting the radiant power (116) through the one or more target gases and through the cell body (114) of the gas detector (100) towards the cavity (112) of the gas detector (100) and the wavelength selective absorber (101) with a reflector;

determining the one or more target gases based on the detected pressure change.

9. The method of claim 8, further comprising providing fluid communication between the pressure sensing element (102) and the cavity (112).

10. The method of claim 8, further comprising allowing a fluid connection between two sides (112-1, 112-2) of the cavity (112) via a through hole (103).

11. The method of claim 8, further comprising determining an amount of radiation absorbed by the one or more target gases based on the detected pressure change.

12. The method of claim 8, further comprising modulating the radiated power (116) at a frequency between 3Hz and 10,000 Hz.

13. The method of claim 8, wherein said providing a gas sealed in a cavity (112) comprises providing nitrogen, hydrogen, argon, krypton, xenon, a hydrocarbon, a fluorocarbon, or a combination thereof.

14. The method of claim 8, further comprising pressurizing the gas sealed in the cavity (112) at a pressure in a range of 0.1 bar to 10 bar.

15. The method of claim 8, wherein directing radiant power (116) from a light source (130) comprises directing radiant power (116) from one or more filament bulbs, micro-electro-mechanical system (MEMS) heating plates, Light Emitting Diodes (LEDs), and/or lasers.